loadAsset error callback & Fluent Block

loadAsset callbacks now has the arguments (err, data). Made Block
Fluent.
Canvas Origin Top-Left Settings

To enable set chesterGL.settings['canvasOriginTopLeft'] = true;
Fixed Canvas Origin Top-Left
Merge branch 'refs/heads/master' into features

Conflicts:
	chesterGL/block.js
chesterGL.Block.setAlpha returns itself. (chaining)
Fixes bug #36
Support for canvas background (with alpha)
Moved gl.clearColor to setBackgroundColor. Added doc for getBackgroundColor.
removing highDPI fonts